drm/amdgpu: use the GTT windows for BO moves v2

This way we don't need to map the full BO at a time any more.

v2: use fixed windows for src/dst

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
index c8059f0..4f5c1da 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
@@ -52,6 +52,8 @@ struct amdgpu_mman {
 	/* buffer handling */
 	const struct amdgpu_buffer_funcs	*buffer_funcs;
 	struct amdgpu_ring			*buffer_funcs_ring;
+
+	struct mutex				gtt_window_lock;
 	/* Scheduler entity for buffer moves */
 	struct amd_sched_entity			entity;
 };